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Heli Hacker's blog
Archive for April, 2010
Posted by Heli Hacker | Apr 22, 2010 @ 09:37 PM | 7,733 Views
This winter I decided to build something that would help me fly better and crash less. Using a 32-bit Parallax Propeller processor and a 2-axis IDG500 gyro, I built myself a virtual flybar unit.

I call it Phubar, for Phase-Universal Flybar.

It allows for adjusting the phase angle of the command inputs and the gyro stabilizing inputs to the swashplate. It has angular gain and rate gain settings (Proportional and Derivative coefficients, for you control systems people) with angular decay so it mimics how a weighted flybar will "follow the heli" after a second or two. The gain, decay, and phasing parameters can be changed using a serial terminal app on the PC that talks to the PhuBar via USB cable.

The whole unit weighs about 13 grams and is 35x35x18mm. By comparison, the stock flybar plus one pair of weights is about 19 grams. It has four receiver inputs - aileron, elevator, aux(pitch), and a spare - and four outputs for servos. An LED lights to tell you when it will accept input via USB, and blinks for 3 seconds when the gyro is calibrating so you know not to move it.

I have tested it on a HBFP and a FireFox Ep200 so far, and it is working very well. It took a lot of test flights for me to find the right gain settings. Photos below show the flybarless head and the PhuBar installed. I made the FBL head for the HBFP by removing the flybar and making direct swash-to-head links using link ends and balls from a FireFox 200. TX and RX are Spectrum....Continue Reading